The present invention relates to the field of wastewater treatment and the like and in particular relates to screening apparatus placed in the flow channels for removing larger materials from waste water passing therethrough. In even greater particularity, the present invention relates to apparatus for cleaning accumulated materials from such screens. In even greater particularity, the present invention relates to a cleaner apparatus for a vertical bar screen.
Bar screens of various configurations are well known in the art and there have been numerous cleaners developed to remove material held by such bar screens. Apparatus of this type which are known to us are generally large and complicated articulated members which depend upon the interaction of a number of jointed members or counter weights to properly position the various components of the apparatus.
For example, U.S. Pat. No. 1,823,823 discloses a screen cleaner, disposed on the upstream side of an inclined bar screen, which includes a rake member pivotally mounted for movement to a position proximal the bar screen responsive to gravity and a counterweight. Clearly, such apparatus was not capable of positively engaging the bar screen to assure removal of the accumulated material, but rather is subject to only partial engagement at the lowermost position on the bar screen. Continued failure to remove the lowermost accumulation in turn leads to greater residual accumulation and diminished capacity of the screen.
Another example of the complex nature of some of the prior art screen cleaners is found in U.S. Pat. No. 4,107,040 wherein a substantially vertical bar screen is cleaned by a rake member which is moved along an asymmetric S curve by a plurality of articulated arms and driven chains which are passed around a number of chain wheels to generate the asymmetric S curve. While this device may positively engage the bar screen, it is somewhat unwieldy and occupies a rather large volume.
Another screen cleaner which is more complex than our device is disclosed in U.S. Pat. No. 4,392,952.
While the aforementioned devices may be in some respects suitable for their intended use and function, they are believed to leave something to be desired in terms of their efficiency, economy, and in some cases, their maintenance and upkeep.